Figure 1. Postulated role of CD73 in Treg-mediated immunosuppression.
(A) Murine Tregs (green) express CD39 and CD73. Extracellular Ado, produced by murine Tregs, can bind to A2A AdoRs on Teffs, causing a rise in intracellular cAMP and suppression of proliferation and inflammatory cytokine production. The purine salvage pathway (which exists in the cytoplasm of all cells) is also illustrated in murine Tregs. HxR, Inosine; Hx, hypoxanthine. (B) Human Tregs (brown) express CD39. Extracellular AMP produced by human Tregs might be converted to extracellular Ado by CD73+CD8+ T cells. This extracellular Ado could then bind to A2A AdoR on CD8+ T cells or Teffs to inhibit their function.